Subjects who present with an influenza-like illness without any risk factors for severe disease will be screened for the study. Those with a confirmatory test for influenza (rapid antigen or polymerase chain reaction [PCR]) will be randomized in a 1:1 manner to receive a blinded study treatment consisting of either the oseltamivir or placebo for 5 days. Clinical, virologic, and laboratory assessments on Days 1, 3, 7, and 28 will be used for both safety and efficacy analysis.